1. Field of the Invention
This invention relates to the art of purifying water and especially deals with a method and apparatus for automatically and sequentially subjecting raw water, such as well water, to a series of treatments which completely or substantially remove both organic and inorganic contaminants, radionuclides, objectionable odors, turbidity and reduce hardness, and to supply upon demand potable water for household or commercial use.
2. The Prior Art
Various processes are currently in use for the treatment of well water to render it suitable for use for boiler feed water, household use and the like. For large installation these processes include:
Cold lime softening. PA2 Cold lime--soda softening. PA2 Hot lime softening. PA2 Hot lime--soda softening. PA2 Hot process phosphate softening. PA2 Ion exchange. PA2 Carbon adsorption. PA2 Coagulation and flocculation. PA2 Sedimentation and clarification. PA2 Filtration. PA2 Aeration. PA2 Chlorination. PA2 Ion exchange. PA2 Distillation. PA2 Reverse osmosis. PA2 Ultrafiltration. PA2 Carbon adsorption. PA2 Coagulation--flocculation. PA2 Permanganate addition. PA2 Filtration. PA2 Chlorination. PA2 Fluoride--Reduced to &lt;0.1 mg/l by co-precipitation with Magnesium Hydroxide. PA2 Arsenic--95% removal by precipitation. PA2 Selenium--50% removal. PA2 Hydrogen--Sulfide--100% removal by oxidation to elemental sufur. PA2 Iron 100% removal by oxidation and precipitation as Fe(OH).sub.3 and Fe.sub.2 (CO.sub.3).sub.3. PA2 Manganese--100% removal by oxidation and precipitation. PA2 Magnesium--Reduced from 80 mg/l to 35 mg/l by precipitation. PA2 Calcium--Reduced from 160 mg/l to 75 mg/l by precipitation. PA2 Silica--50% removal by co-precipitation with Mg(OH).sub.2. PA2 Radium 226 and 228--reduced from 12 p Ci/l to &lt;1 p Ci/l. (Picocuries/liter) PA2 Gross.alpha.--Radiation reduced from 50 p Ci/l to 3 p Ci/l. PA2 Gross B--Radiation reduced from 60 p Ci/1 to &lt;8 p Ci/1. PA2 Chloroform PA2 Benzene PA2 Bromoform PA2 Carbon Tetrachloride PA2 Chlorobenzene PA2 Perchloroethylene PA2 Hexane PA2 Decane PA2 Fulvic Acid PA2 Humic Acid PA2 Odor--Removed of H.sub.2 S (rotten egg smell) and volatile organics.
The operations required for these processes usually include:
These processes require large complicated chemical treatment apparatus that must be serviced by skilled operators and are so expensive that they can only be afforded by large, municipal and commercial users.
For smaller installations the processes used are:
The operations used with these processes are:
These processes are normally problem specific i.e. permanganate addition and filtration for iron removal, ion exchange for hardness removal, reverse osmosis or distillation for dissolved solids reduction and carbon adsorption for odor and taste removal. Equipment costs and operating costs are high for the volume of water treated, and the equipment requires frequent maintenance and parts replacement.
It would therefore be an improvement in this art to provide an automatic water treatment system sufficiently low in cost, small, simple and reliable in operation as to be useful in single family homes and commercial plants to convert an otherwise undesirable water source into high quality potable water, useable on demand.
While lime and monosodium phosphate are the preferred chemicals to achieve the desired water quality in the final product, the lime may be in the form of calcium oxide or calcium hydroxide. Monosodium phosphate may be replaced wholly or in part with almost any acid such as sulfuric, hydrochloride or phosphoric. Such acids, however, may cause difficulty in controlling the pH of the product. For example, if the pH becomes less than 7 the anions will become soluble and remain in the treated water.